Traditional and widely used disposable food packages and containers are made from closed-cell extruded polystyrene foams. Because they are entirely made out of plastic, they do not biodegrade and thus, have a negative impact on the environment. Some regulations have banned the use of such packages and containers, for environmental reasons.
A more environmentally sound alternative food packages are made from a more renewable substrate, such as cellulosic sheet, e.g., paperboard, cardboard, paper, coated paper, films, bonded together with an adhesive. The alternative packages typically comprise at least two cellulosic substrates with an air gap interposed between the two substrates. As the package is handled and flexed, the air gap between the two substrates become compressed and the insulation is decreased in those compressed areas. To improve the insulative properties of the package, a divider (e.g., medium) can be placed in between the two substrates as a support structure or higher basis weight substrates or non-recycled paperboards may be used as the substrates. However, the aforementioned solutions increase cost and also increase carbon footprint.
The present invention seeks to improve insulating cellulosic sheet, through the use of an adhesive composition that adds insulative properties and structural integrity to the cellulosic sheet. The present invention provides an environmentally and economically sound package that provides thermal insulation and structural integrity.